Mouth exercisers are known in the art. However, existing mouth exercisers often only permit a user to exercise their mouth and jaw at a single resistive force. Further, many mouth exercisers known in the art are only available as a “one-size-fits-all” type of device. Accordingly, when exercising at higher resistive forces, injury to the teeth, mouth, and face resulting from misalignment or slippage of the device may occur. Thus, a need exists in the art for a variable resistive force mouth exerciser that may be adapted to fit a user's particular mouth. The mouth exerciser of the present disclosure is aimed at overcoming this and other needs in the art.